Kinase classification

Protein Kinases have a wide variety of functions and can be classified by function and by the sequence similarity. We use a hierarchical system of classifying kinases into groups, which consist of multiple families, which sometimes have several subfamilies. Here we outline the 10 groups of protein kinases

AGC

Named after the Protein Kinase A, G, and C families (PKA, PKC, PKG), this group contains many core intracellular signaling kinases which are modulated by cyclic nucleotides, phospholipids and calcium.

CMGC

Named after another set of families (CDK, MAPK, GSK3 and CLK), this group has a diversity of functions in cell cycle control, MAPK signaling, splicing and other unknown functions.

CAMK

Best known for the Calmodulin/Calcium regulated kinases (CAMK) in CAMK1 and CAMK2 families, this also has several families of non-calcium regulated kinases.

CK1

A small but ancient family. Originally known as Casein Kinase 1 (from a biochemically assay with a non-physiological substrate), and now re-named to Cell Kinase 1.

Other

This group consists of several families, and some unique kinases that are clearly ePKs but do not fit into the other ePK groups.

STE

Homologs of the yeast STE7, STE11 and STE20 genes, which form the MAPK cascade, transducing signals from the surface of the cell to the nucleus.

Tyrosine Kinase (TK)

This group phosphorylates almost exclusively on tyrosine residues, as opposed to most other kinases that are selective for serine or threonine

Tyrosine Kinase-Like (TKL)

The group most similar to tyrosine kinases, but whose activities are generally on serine/threonine substrates.

RGC

Receptor Guanylate Cyclases. This small group contains an active guanylate cyclase domain, which generates the cGMP second messenger, and a catalytically inactive kinase domain, which appears to have a regulatory function.

Atypical

Diverse group of kinases with little or no sequence similarity to ePKs. Several families have structural similarity to the ePK domain, and others have completely distinct, or undiscovered structures.